Biodegradable polymers are essential materials for a wide variety of biomedical applications including tissue engineering where cell seeded constructs are designed to replace damaged or diseased tissue. These constructs often must provide stability and structural integrity within a mechanically dynamic environment without irritation to the host. Consequently, there is a considerable need and interest in developing tough biodegradable elastomers which exhibit mechanical properties similar to those of soft tissue. Common biodegradable elastomers include, poly(glycerol sebacate), poly(citric diol), star-poly(r-caprolactone-co-D,L-lactide), poly(tri-methylene carbonate-co-ε-caprolactone) and poly(tri-methylene carbonate-co-D,L-lactide).
These elastomers, however, have mechanical properties, e.g., as reflected in their elongation % and Young's modulus, that can render them insufficient for many biomedical applications if their biodegradability is to be maintained. For example, as mechanical strength is often proportional to polymer crosslink density, whereas degradability is often inversely proportional to crosslink density, providing a material with both acceptable mechanical strength and degradability is difficult.
Further, these biodegradable elastomers often must be cured at high temperatures in vacuo for extended periods of time (e.g., 24 h) to produce materials with acceptable mechanical properties. This, however, can preclude their use in applications where incorporation of a temperature sensitive component, e.g., a drug, growth factors, cells, etc. is desired. In addition, polymer transitions through a melt phase upon high temperature curing and can produce bubbles which limit the complexity of shapes that can be achieved.